1 // target.h -- target support for gold -*- C++ -*-
3 // Copyright 2006, 2007 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
8 // This program is free software; you can redistribute it and/or modify
9 // it under the terms of the GNU General Public License as published by
10 // the Free Software Foundation; either version 3 of the License, or
11 // (at your option) any later version.
13 // This program is distributed in the hope that it will be useful,
14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
16 // GNU General Public License for more details.
18 // You should have received a copy of the GNU General Public License
19 // along with this program; if not, write to the Free Software
20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
21 // MA 02110-1301, USA.
23 // The abstract class Target is the interface for target specific
24 // support. It defines abstract methods which each target must
25 // implement. Typically there will be one target per processor, but
26 // in some cases it may be necessary to have subclasses.
28 // For speed and consistency we want to use inline functions to handle
29 // relocation processing. So besides implementations of the abstract
30 // methods, each target is expected to define a template
31 // specialization of the relocation functions.
41 class General_options;
43 template<int size, bool big_endian>
45 template<int size, bool big_endian>
52 // The abstract class for target specific handling.
60 // Return the bit size that this target implements. This should
64 { return this->pti_->size; }
66 // Return whether this target is big-endian.
69 { return this->pti_->is_big_endian; }
71 // Machine code to store in e_machine field of ELF header.
74 { return this->pti_->machine_code; }
76 // Whether this target has a specific make_symbol function.
78 has_make_symbol() const
79 { return this->pti_->has_make_symbol; }
81 // Whether this target has a specific resolve function.
84 { return this->pti_->has_resolve; }
86 // Whether this target has a specific code fill function.
89 { return this->pti_->has_code_fill; }
91 // Return the default name of the dynamic linker.
93 dynamic_linker() const
94 { return this->pti_->dynamic_linker; }
96 // Return the default address to use for the text segment.
98 text_segment_address() const
99 { return this->pti_->text_segment_address; }
101 // Return the ABI specified page size.
104 { return this->pti_->abi_pagesize; }
106 // Return the common page size used on actual systems.
108 common_pagesize() const
109 { return this->pti_->common_pagesize; }
111 // This is called to tell the target to complete any sections it is
112 // handling. After this all sections must have their final size.
114 finalize_sections(Layout* layout)
115 { return this->do_finalize_sections(layout); }
117 // Return a string to use to fill out a code section. This is
118 // basically one or more NOPS which must fill out the specified
121 code_fill(off_t length)
122 { return this->do_code_fill(length); }
125 // This struct holds the constant information for a child class. We
126 // use a struct to avoid the overhead of virtual function calls for
127 // simple information.
130 // Address size (32 or 64).
132 // Whether the target is big endian.
134 // The code to store in the e_machine field of the ELF header.
135 elfcpp::EM machine_code;
136 // Whether this target has a specific make_symbol function.
137 bool has_make_symbol;
138 // Whether this target has a specific resolve function.
140 // Whether this target has a specific code fill function.
142 // The default dynamic linker name.
143 const char* dynamic_linker;
144 // The default text segment address.
145 uint64_t text_segment_address;
146 // The ABI specified page size.
147 uint64_t abi_pagesize;
148 // The common page size used by actual implementations.
149 uint64_t common_pagesize;
152 Target(const Target_info* pti)
156 // Virtual function which may be implemented by the child class.
158 do_finalize_sections(Layout*)
161 // Virtual function which must be implemented by the child class if
165 { gold_unreachable(); }
168 Target(const Target&);
169 Target& operator=(const Target&);
171 // The target information.
172 const Target_info* pti_;
175 // The abstract class for a specific size and endianness of target.
176 // Each actual target implementation class should derive from an
177 // instantiation of Sized_target.
179 template<int size, bool big_endian>
180 class Sized_target : public Target
183 // Make a new symbol table entry for the target. This should be
184 // overridden by a target which needs additional information in the
185 // symbol table. This will only be called if has_make_symbol()
187 virtual Sized_symbol<size>*
189 { gold_unreachable(); }
191 // Resolve a symbol for the target. This should be overridden by a
192 // target which needs to take special action. TO is the
193 // pre-existing symbol. SYM is the new symbol, seen in OBJECT.
194 // VERSION is the version of SYM. This will only be called if
195 // has_resolve() returns true.
197 resolve(Symbol*, const elfcpp::Sym<size, big_endian>&, Object*,
199 { gold_unreachable(); }
201 // Scan the relocs for a section, and record any information
202 // required for the symbol. OPTIONS is the command line options.
203 // SYMTAB is the symbol table. OBJECT is the object in which the
204 // section appears. DATA_SHNDX is the section index that these
205 // relocs apply to. SH_TYPE is the type of the relocation section,
206 // SHT_REL or SHT_RELA. PRELOCS points to the relocation data.
207 // RELOC_COUNT is the number of relocs. LOCAL_SYMBOL_COUNT is the
208 // number of local symbols. PLOCAL_SYMBOLS points to the local
209 // symbol data from OBJECT. GLOBAL_SYMBOLS is the array of pointers
210 // to the global symbol table from OBJECT.
212 scan_relocs(const General_options& options,
213 Symbol_table* symtab,
215 Sized_relobj<size, big_endian>* object,
216 unsigned int data_shndx,
217 unsigned int sh_type,
218 const unsigned char* prelocs,
220 size_t local_symbol_count,
221 const unsigned char* plocal_symbols,
222 Symbol** global_symbols) = 0;
224 // Relocate section data. SH_TYPE is the type of the relocation
225 // section, SHT_REL or SHT_RELA. PRELOCS points to the relocation
226 // information. RELOC_COUNT is the number of relocs. VIEW is a
227 // view into the output file holding the section contents,
228 // VIEW_ADDRESS is the virtual address of the view, and VIEW_SIZE is
229 // the size of the view.
231 relocate_section(const Relocate_info<size, big_endian>*,
232 unsigned int sh_type,
233 const unsigned char* prelocs,
236 typename elfcpp::Elf_types<size>::Elf_Addr view_address,
237 off_t view_size) = 0;
240 Sized_target(const Target::Target_info* pti)
243 gold_assert(pti->size == size);
244 gold_assert(pti->is_big_endian ? big_endian : !big_endian);
248 } // End namespace gold.
250 #endif // !defined(GOLD_TARGET_H)